The present invention relates to the construction of micro-electro mechanical devices such as inkjet printers and in particular discloses a process of electrical isolation of components from a fluid reservoir.
Various methods, systems and apparatus relating to the present invention are disclosed in the following co-pending applications filed by the applicant or assignee of the present invention: 09/575,197 09/575,195 09/575,132 09/575,123 09/575,148 09/575,130 09/575,165 09/575,153 09/575,118 09/575,131 09/575,116 09/575,144 09/575,139 09/575,186 09/575,185 09/575,191 09/575,145 09/575,192 09/575,181 09/575,193 9/575,156 09/575,183 09/575,160 09/575,150 09/575,169 09/575,184 09/575,128 09/575,180 09/575,149 09/575,179 09/575,133 09/575,143 09/575,187 09/575,155 09/575,196 09/575,198 09/575,178 09/575,164 09/575,146 09/575,174 09/575,163 09/575,168 09/575,154 09/575,129 09/575,124 09/575,188 09/575,189 09/575,162 09/575,172 09/575,170 09/575,171 09/575,161 09/575,141 09/575,125 09/575,142 09/575,140 09/575,190 09/575,138 09/575,126 09/575,127 09/575,158 09/575,117 09/575,147 09/575,152 09/575,176 09/575,151 09/575,177 09/575,175 09/575,115 09/575,114 09/575,113 09/575,112 09/575,111 09/575,108 09/575,109 09/575,182 09/575,173 09/575,194 6,238,043 09/575,119 09/575,135 09/575,157 09/575,166 09/575,134 09/575,121 09/575,137 09/575,167 09/575,120 09/575,122
The disclosures of these co-pending applications are incorporated herein by reference.
Recently, for example, in PCT Application No. PCT/AU98/00550 the present applicant has proposed an inkjet printing device which utilizes micro-electromechanical (MEMS) processing techniques in the construction of a thermal bend actuator type device for the ejection of fluid from a nozzle chamber.
In any such thermal actuator type device, it is often the case that the thermal bend actuator is operated via the selective resistive heating of an element The utilization of conductive heating elements near a fluid supply may lead to problems whereby the fluid supply interferes with the electron flow in the conductive element and electrolysis results. This can result in a general breakdown of the actuator leading to catastrophic failure.
There is disclosed herein an ink jet printhead comprising a plurality of nozzle devices formed on a substrate, each nozzle device comprising:
a nozzle chamber,
a nozzle opening through which ink from the nozzle chamber is ejected,
a movable element in contact with ink in the nozzle chamber to cause said ejection of ink,
a thermal bend actuator having a proximal end anchored to the substrate and a distal end connected to the movable element, the actuator including a first portion adjacent the proximal end external to the nozzle chamber and having a conductive heating circuit layer for heating the actuator, and a second portion extending to said movable element and in contact with said ink,
wherein said actuator includes a dielectric means for electrically isolating said first and second portions so that electric energy in said heating circuit layer is not conducted by the actuator to said ink.
Preferably said dielectric means comprises a slot extending across the thermal bend actuator.
Preferably said conductive heating circuit layer is substantially planar.
Preferably said conducting heating layer comprises substantially titanium nitride.
Preferably said conductive heating circuit includes at least one tapered portion adjacent said proximal end arranged to increase resistive heating adjacent said proximal end.
Preferably said movable element is an ink ejection paddle located within the nozzle chamber and movable toward said nozzle opening to eject ink.
Alternatively said movable portion includes the nozzle opening and move towards the substrate to cause ejection of ink through the nozzle opening.
Preferably each nozzle device comprises a crown portion defining the nozzle opening and a skirt portion depending from the crown portion, the skirt portion forming a first part of a peripheral wall of the nozzle chamber.
Preferably the printhead includes an ink inlet aperture defined in a floor of the nozzle chamber and a bounding wall surrounding the aperture and defining a second part of the peripheral wall of the nozzle chamber.
Preferably the skirt portion is displaceable relative to the substrate and said bounding wall serves as an inhibiting means for inhibiting leakage of ink from the chamber.
Preferably said dielectric means is located external to the nozzle chamber. There is further disclosed herein an ink jet printhead comprising a plurality of nozzle devices formed on a substrate, each nozzle device comprising:
a nozzle chamber,
a nozzle opening through which ink from the nozzle chamber is ejected,
a movable element in contact with ink in the nozzle chamber to cause said ejection of ink,
a thermal bend actuator having a proximal end anchored to the substrate and a distal end connected to the movable element, the actuator including a first portion adjacent the proximal end external to the nozzle chamber and having a conductive heating circuit layer for heating the actuator, and a second portion extending to said movable element and in contact with said ink,
wherein said first and second portions are electrically isolated from one another so that electric energy in said heating circuit layer is not conducted by the actuator to said ink.